1. Field of the Invention
This invention relates to a method and apparatus for removing micronized coal from steam used to pulverize coal by spraying petroleum oil into a stream of the coal-bearing steam and separating the coal and oil from the steam in the form of a coal-oil slurry through the use of impact or centrifugal forces.
2. Prior Art
It is becoming increasingly common to mix pulverized coal with oil for use as an industrial fuel. The finely divided coal required can be produced by fluid energy mills which utilize high pressure steam to reduce the size of the coal particles through high speed collision and refraction. The discharge of the mill is fed to cyclones which separate the pulverized coal from the steam for mixing with the oil in proper proportion for the desired fuel mixture.
Unfortunately, however, steam exiting the cyclones is ladden with large quantities of micron and submicron sized coal particles. Recovery of this residual coal is important because the fine coal particles are highly explosive, are valuable for increasing the yield of the process of making the coal-oil mixture and cannot be released into the atmosphere under existing pollution regulations. The conventional collectors for suspended particulates, such as scrubbers, baghouses, condensors and electrostatic precipitators, cannot remove the micronized coal particles from the steam effectively without danger of fires, explosions and water pollution.